Magnetic field detection device

ABSTRACT

Provided is a magnetic field detection device that includes a first and second soft magnetic bodies, and a magnetic detector. The first and second soft magnetic bodies extend along a first plane and are disposed in confronted relation in a third direction. The first plane includes both a first direction and a second direction orthogonal to the first direction. The third direction is orthogonal to both the first and second directions. The magnetic detector is provided between the first and second soft magnetic bodies in the third direction.

CROSS REFERENCE TO RELATED APPLICATIONS

This is a Continuation of U.S. application Ser. No. 16/692,138, filedNov. 22, 2019, which is a Continuation of U.S. application Ser. No.15/688,093, filed Aug. 28, 2017, and claims the benefit of JapanesePriority Patent Application JP2016-208785, filed on Oct. 25, 2016. Theentire contents of the above applications are incorporated herein byreference.

BACKGROUND

The invention relates to a magnetic field detection device that detectsa magnetic field using a magnetic detector.

Magnetic field detection devices detect external magnetic fields. As themagnetic field detection devices, known are those that utilize Hallelements or magneto-resistive effect elements. For example, reference ismade to International Publication No. WO2008/146809.

SUMMARY

In recent years, there has been a desire for enhancement in performanceof magnetic field detection. It is therefore desirable to provide amagnetic field detection device that has more optimal performance ofmagnetic field detection.

A magnetic field detection device according to an illustrativeembodiment of the invention includes a first soft magnetic body and asecond soft magnetic body, and a magnetic detector. The first softmagnetic body and the second soft magnetic body extend along a firstplane and are disposed in confronted relation in a third direction. Thefirst plane includes both a first direction and a second directionorthogonal to the first direction. The third direction is orthogonal toboth the first direction and the second direction. The magnetic detectoris provided between the first soft magnetic body and the second softmagnetic body in the third direction.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a schematic perspective view of an overall configuration of amagnetic field detection device according to a first embodiment of theinvention.

FIG. 1B is a cross-sectional view of a cross-sectional configuration ofthe magnetic field detection device illustrated in FIG. 1A.

FIG. 2 is an enlarged cross-sectional view of a cross-sectionalconfiguration of a magnetic detector illustrated in FIG. 1A.

FIG. 3 is a circuit diagram of an example of a signal detection circuitmounted on the magnetic field detection device illustrated in FIG. 1A.

FIG. 4A is a schematic perspective view of an overall configuration of amagnetic field detection device according to a second embodiment of theinvention.

FIG. 4B is a cross-sectional view of a cross-sectional configuration ofthe magnetic field detection device illustrated in FIG. 4A.

FIG. 5A is a perspective view of a modification example (a firstmodification example) of the magnetic field detection device illustratedin FIGS. 4A and 4B.

FIG. 5B is a cross-sectional view of a cross-sectional configuration ofthe magnetic field detection device illustrated in FIG. 5A.

FIG. 6 is a cross-sectional view of a modification example (a secondmodification example) of the magnetic field detection device illustratedin FIGS. 4A and 4B.

FIG. 7 is a cross-sectional view of a modification example (a thirdmodification example) of the magnetic field detection device illustratedin FIGS. 4A and 4B.

FIG. 8 is a cross-sectional view of a modification example (a fourthmodification example) of the magnetic field detection device illustratedin FIGS. 4A and 4B.

FIG. 9A is a characteristic diagram that illustrates distribution ofmagnetic field strength in a magnetic field detection device accordingto an experimental example 1-1.

FIG. 9B is a characteristic diagram that illustrates distribution ofmagnetic field strength in a magnetic field detection device accordingto an experimental example 1-2.

FIG. 9C is a characteristic diagram that illustrates distribution ofmagnetic field strength in a magnetic field detection device accordingto an experimental example 1-3.

FIG. 9D is a characteristic diagram that illustrates distribution ofmagnetic field strength in a magnetic field detection device accordingto an experimental example 1-4.

FIG. 9E is a characteristic diagram that illustrates distribution ofmagnetic field strength in a magnetic field detection device accordingto an experimental example 1-5.

FIG. 10 is a characteristic diagram that illustrates distribution ofmagnetic field strength in a magnetic field detection device accordingto an experimental example 2-1.

FIG. 11 is a characteristic diagram that illustrates distribution ofmagnetic field strength in a magnetic field detection device accordingto an experimental example 2-2.

FIG. 12 is a characteristic diagram that illustrates critical magneticfield strength in magnetic field detection devices according toexperimental examples 3-1 to 3-8.

FIG. 13A is a schematic diagram that illustrates a first modificationexample of a planar shape of a soft magnetic body.

FIG. 13B is a schematic diagram that illustrates a second modificationexample of a planar shape of a soft magnetic body.

FIG. 13C is a schematic diagram that illustrates a third modificationexample of a planar shape of a soft magnetic body.

FIG. 13D is a schematic diagram that illustrates a fourth modificationexample of a planar shape of a soft magnetic body.

FIG. 14A is a cross-sectional view of a magnetic field detection deviceaccording to a fifth modification example.

FIG. 14B is a cross-sectional view of a magnetic field detection deviceaccording to a sixth modification example.

DETAILED DESCRIPTION

Some example embodiments of the invention are described in detail belowwith reference to the accompanying drawings. The description is given inthe following order.

1. First Embodiment

An example of a magnetic field detection device including a pair of softmagnetic layers each including a flat surface

2. Second Embodiment and its Modification Examples

2.1 An example of a magnetic field detection device including a pair ofsoft magnetic layers each including a flat surface and a protrusionprovided thereon

2.2 First Modification Example (an example of a magnetic field detectiondevice including a plurality of magnetic detectors interposed between apair of soft magnetic layers)

2.3 Second Modification Example (an example with the protrusionsprovided solely on one of the soft magnetic layers)

2.4 Third Modification Example (an example in which the soft magneticlayers including the protrusions of other shapes)

2.5 Fourth Modification Example (an example with the protrusionsarranged at different pitches on the pair of the soft magnetic layers)

3. Experimental Examples 4. Other Modification Examples 1. FirstEmbodiment Configuration of Magnetic Field Detection Device 1

Description is given first of a configuration of a magnetic fielddetection device 1 according to a first embodiment of the invention,with reference to the figures such as FIGS. 1A, 1B, and 2. FIG. 1A is aperspective view of an example of an overall configuration of themagnetic field detection device 1. FIG. 1B illustrates an example of across-sectional configuration of the magnetic field detection device 1viewed in a direction of an arrow along a line IB-IB illustrated in FIG.1A. FIG. 2 illustrates an example of a cross-sectional configuration ofa magnetic detector 20 illustrated in FIGS. 1A and 1B.

The magnetic field detection device 1 may be a device that detectspresence or absence of an external magnetic field that covers themagnetic field detection device 1 itself, and detects a direction orstrength, or other properties of the external magnetic field. Themagnetic field detection device 1 may be mounted on an electromagneticcompass, without limitation. The magnetic field detection device 1includes a pair of soft magnetic layers 11 and 12, and the magneticdetector 20. The pair of the soft magnetic layers 11 and 12 are disposedin confronted relation in, for example, a Z axis direction. The magneticdetector 20 is provided between the soft magnetic layer 11 and the softmagnetic layer 12 in the Z axis direction. The magnetic field detectiondevice 1 may further include leads 21 and 22 that cause a sense currentto flow to the magnetic detector 20. It is to be noted that in FIG. 2,illustration of the leads 21 and 22 is omitted.

Soft Magnetic Layers 11 and 12

The soft magnetic layers 11 and 12 both extend along an X-Y plane thatis orthogonal to the Z axis direction. The soft magnetic layers 11 and12 may be made of, for example but not limited to, a soft magnetic metalmaterial having high saturation magnetic flux density, e.g., anickel-iron alloy (Ni—Fe). As illustrated in FIG. 1A, the soft magneticlayers 11 and 12 are rectangular in planar shapes in the X-Y plane. Inone preferable but non-limiting example, a ratio (LX/LY) of a dimensionLX to a dimension LY may range from 1 to 4 both inclusive, in which LXdenotes a dimension in an X axis direction, and LY denotes a dimensionin a Y axis direction. In other words, in one preferable butnon-limiting example, the following conditional expression [1] may besatisfied,

1≤LX/LY≤4   [1]

This makes it possible for the soft magnetic layers 11 and 12 to serveas magnetic shields that restrain more effectively an external magneticfield in the Y axis direction from covering the magnetic detector 20.Accordingly, in using the magnetic field detection device 1, in onepreferable but non-limiting example, the Y axis direction may coincidewith a direction of an unwanted external magnetic field component in adifferent direction from an external magnetic field component as atarget of detection. Setting a posture or orientation of the magneticfield detection device 1 in this way makes it possible to magneticallyshield the magnetic detector 20 against the unwanted external magneticfield component. The soft magnetic layer 11 may include a flat surface11S that is confronted with the soft magnetic layer 12, whereas the softmagnetic layer 12 may include a flat surface 12S that is confronted withthe soft magnetic layer 11. Both the flat surface 11S and the flatsurface 12S may be substantially parallel to the X-Y plane.

Magnetic Detector 20

The magnetic detector 20 may be, for example but not limited to, amagneto-resistive effect (MR) element that exhibits a change inresistance in accordance with the direction or the strength of theexternal magnetic field. As illustrated in, for example, FIG. 2, themagnetic detector 20 may be a current perpendicular to plane (CPP) MRelement of a spin valve structure including a stack of a plurality offunctional films including a magnetic layer, and allow the sense currentto flow through an inside of itself in a stacking direction. In onespecific but non-limiting example, as illustrated in FIG. 2, themagnetic detector 20 may include a stacked body in which anantiferromagnetic layer 31, a magnetization fixed layer 32, anintermediate layer 33, and a magnetization free layer 34 are stacked inorder. The magnetization fixed layer 32 may have magnetization fixed ina constant direction. The intermediate layer 33 may exhibit no specificdirection of magnetization. The magnetization free layer 34 may havemagnetization that changes with the external magnetic field. It is to benoted that the antiferromagnetic layer 31, the magnetization fixed layer32, the intermediate layer 33, and the magnetization free layer 34 mayeach have either a single-layer structure or a multi-layered structureincluding a plurality of layers. In the MR element as described above,the change in resistance occurs in accordance with a change in amagnetic flux along an in-plane direction of the films that isorthogonal to the stacking direction. In one preferable but non-limitingexample, as described in and after a second embodiment, with thestacking direction of the magnetic detector 20 being the Z axisdirection in the magnetic field detection device 1, protrusions or otherstructures may be provided, in order to cause the change in theresistance to occur in accordance with the change in a magnetic flux F(FIG. 1B) in the Z axis direction. The protrusions or other structuresmay be able to bend, in the vicinity of the magnetic detector 20, adirection of the magnetic flux F along an in-plane direction of the X-Yplane. The in-plane direction of the X-Y plane serves as direction ofmagnetic sensing.

The antiferromagnetic layer 31 may be made of an antiferromagneticmaterial such as a platinum-manganese alloy (Pt—Mn) and aniridium-manganese alloy (Ir—Mn). The antiferromagnetic layer 31 may bein a state in which, for example, a spin magnetic moment in thesubstantially same direction as the direction of the magnetization ofthe magnetization fixed layer 32 in adjacency thereto and a spinmagnetic moment in an opposite direction thereto cancel each othercompletely. Thus, the antiferromagnetic layer 31 may act to fix thedirection of the magnetization of the magnetization fixed layer 32 inthe constant direction.

The magnetization fixed layer 32 may be made of a ferromagnetic materialsuch as cobalt (Co), a cobalt-iron alloy (Co—Fe), a cobalt-iron-boronalloy (Co—Fe—B).

The intermediate layer 33 may be a non-magnetic tunnel barrier layermade of, for example but not limited to, magnesium oxide (MgO), in acase where the magnetic detector 20 is a magnetic tunneling junction(MTJ) element. The intermediate layer 33 may be thin enough to allow atunneling current based on quantum mechanics to pass through. The MgOtunneling barrier layer may be produced by, for example, a sputteringprocess using an MgO target. In addition, the MgO tunneling barrierlayer may be produced by an oxidization process of a magnesium (Mg) thinfilm, or a reactive sputtering process that involves magnesiumsputtering in an oxygen atmosphere. Moreover, in addition to MgO, theintermediate layer 33 may be constituted with the utilization of anoxide or a nitride of aluminum (Al), tantalum (Ta), and/or hafnium (Hf).Furthermore, the intermediate layer 33 may be made of a non-magnetichighly conductive material such as copper (Cu), ruthenium (Ru), and gold(Au), in a case where the magnetic detector 20 is, for example, a giantmagnetoresistive (GMR) element.

The magnetization free layer 34 may be a soft ferromagnetic layer, andhave an axis of easy magnetization that is substantially orthogonal to,for example, the direction of the magnetization of the magnetizationfixed layer 32. The magnetization free layer 34 may be made of, forexample but not limited to, the cobalt-iron alloy (Co—Fe), thenickel-iron alloy (Ni—Fe), or the cobalt-iron-boron alloy (Co—Fe—B).

Leads 21 and 22

The lead 21 may extend in the X-Y plane, to be in contact with one endsurface of the magnetic detector 20, e.g., the magnetization free layer34. The lead 22 may extend in the X-Y plane, to be in contact withanother end surface of the magnetic detector 20, e.g., theantiferromagnetic layer 31. The leads 21 and 22 may be made of, forexample but not limited to, a highly conductive non-magnetic materialsuch as copper and aluminum (Al).

Arrangement Position of Magnetic Detector 20

As illustrated in FIG. 1B, in the magnetic field detection device 1, inone preferable but non-limiting example, angles A1 and A2 formed bystraight lines LA1 and LA2 with respect to the flat surface 11S may eachbe equal to or smaller than 45°. The straight line LA1 and LA2respectively couple the magnetic detector 20 to edges 11T1 and 11T2 ofthe flat surface 11S. The edges 11T1 and 11T2 are located on both endsof the flat surface 11S in the Y axis direction. Furthermore, angles B1and B2 formed by straight lines LB1 and LB2 with respect to the flatsurface 12S may each be equal to or smaller than 45°. The straight linesLB1 and LB2 respectively couple the magnetic detector 20 to edges 12T1and 12T2 of the flat surface 12S. The edges 12T1 and 12T2 are located onboth ends of the flat surface 12S in the Y axis direction. In otherwords, in one preferable but non-limiting example, the magnetic detector20 may be disposed in space surrounded by the four straight lines LA1,LA2, LB1, and LB2 illustrated in FIG. 1B. This makes it possible for thesoft magnetic layers 11 and 12 to sufficiently shield the magneticdetector 20 against the external magnetic field component in the Y axisdirection. It is to be noted that as illustrated in FIG. 1B, the edge11T1 may be a part where an end surface 11E1 and the flat surface 11Scross each other. The edge 11T2 may be a part where an end surface 11E2and the flat surface 11S cross each other. Likewise, the edge 12T1 maybe a part where an end surface 12E1 and the flat surface 12S cross eachother. The edge 12T2 may be a part where an end surface 12E2 and theflat surface 12S cross each other. The edges 11T1, 11T2, 12T1, and 12T2may all extend straightly in the X axis direction.

In one preferable but non-limiting example, as illustrated in FIG. 1B,in a case where in the Z axis direction, positions of the edges 11T1 and11T2 of the soft magnetic layer 11 and positions of the edges 12T1 and12T2 of the soft magnetic layer 12 substantially coincide with eachother, the following conditional expression [2] may be satisfied. Thismakes it possible, in this case as well, to shield the magnetic detector20 against the external magnetic field component in the Y axisdirection.

L≥D/2   [2]

In the expression, L denotes a distance from the edge 11T1 or 11T2 tothe magnetic detector 20 in the Y axis direction, and D denotes adistance from the flat surface 11S to the flat surface 12S (refer toFIG. 1B).

Signal Detection Circuit

The magnetic field detection device 1 may include a signal detectioncircuit as illustrated in, for example, FIG. 3. The signal detectioncircuit may include, for example but not limited to, a voltageapplicator unit 101, the magnetic detector 20, a resistance changedetector unit 102, and a signal processor unit 103. The voltageapplicator unit 101 and the resistance change detector unit 102 may becoupled to the magnetic detector 20. The signal processor unit 103 maybe coupled to the resistance change detector unit 102.

Workings and Effects of Magnetic Field Detection Device 1

In the magnetic field detection device 1, by the signal detectioncircuit as described above, obtained is an output in accordance with theexternal magnetic field that covers the magnetic field detection device1. In one specific but non-limiting example, in the signal detectioncircuit as mentioned above, a predetermined voltage is applied by thevoltage applicator unit 101 to between the lead 21 and the lead 22,causing the flow of the sense current that corresponds to electricalresistance of the magnetic detector 20 at that time. The electricalresistance of the magnetic detector 20 changes with a state ofmagnetization of the magnetic detector 20, i.e., the direction of themagnetization of the magnetization free layer 34 with respect to thedirection of the magnetization of the magnetization fixed layer 32. Thesense current that flows through the magnetic detector 20 is detected inthe resistance change detector unit 102, causing a signal to beoutputted by the resistance change detector unit 102 to the signalprocessor unit 103. Furthermore, in the signal processor unit 103,generated is a signal based on the output from the resistance changedetector unit 102. The signal thus generated is outputted to outside.Thus, an output in accordance with the external magnetic field thatcovers the magnetic field detection device 1 is obtained from the signaldetection circuit.

In the magnetic field detection device 1 according to this embodiment,the pair of the soft magnetic layers 11 and 12 are provided. The softmagnetic layer 11 and the soft magnetic layer 12 are disposed inconfronted relation, with the magnetic detector 20 interposedtherebetween in the Z axis direction. Accordingly, the soft magneticlayer 11 and the soft magnetic layer 12 both act as magnetic yokes withrespect to the external magnetic field component in the Z axisdirection. Meanwhile, the soft magnetic layer 11 and the soft magneticlayer 12 both act as magnetic shields against the external magneticfield component in the Y axis direction. In other words, according tothe magnetic field detection device 1, the soft magnetic layer 11 andthe soft magnetic layer 12 exhibit a shielding effect against theexternal magnetic field component in the Y axis direction, whileenhancing the external magnetic field component in the Z axis direction.Hence, it is possible to exhibit high performance in the magnetic fielddetection with respect to the external magnetic field component in the Zaxis direction.

2. Second Embodiment 2.1 Magnetic Field Detection Device 2

Description is given next of a configuration of a magnetic fielddetection device 2 according to a second embodiment of the invention,with reference to FIGS. 4A and 4B. FIG. 4A is a perspective view of anexample of an overall configuration of the magnetic field detectiondevice 2. FIG. 4B illustrates a configuration example of a Y-Zcross-section of the magnetic field detection device 2 viewed in adirection of an arrow along a line IVB-IVB illustrated in FIG. 4A.

In the magnetic field detection device 2 according to this embodiment, aprotrusion 11P may be provided on the flat surface 11S of the softmagnetic layer 11, whereas a protrusion 12P may be provided on the flatsurface 12S of the soft magnetic layer 12. Furthermore, the stackingdirection of the MR element as the magnetic detector 20 may be the Zaxis direction, with the lead 21 being coupled to an upper surface ofthe magnetic detector 20, and with the lead being coupled to a lowersurface of the magnetic detector 20. Otherwise, the magnetic fielddetection device 2 may have substantially similar configurations tothose of the magnetic field detection device 1 according to the forgoingfirst embodiment.

As illustrated in FIGS. 4A and 4B, the protrusion 11P may be verticallyprovided on the flat surface 11S, to protrude toward the flat surface12S. Meanwhile, the protrusion 12P may be vertically provided on theflat surface 12S, to protrude toward the confronted flat surface 11S.However, the protrusion 11P and the protrusion 12P may be provided atdifferent positions from each other in the X-Y plane. Moreover, themagnetic detector 20 may be disposed at a position interposed betweenthe protrusion 11P and the protrusion 12P in the X-Y plane, and in the Yaxis direction in this example.

As described, in the magnetic field detection device 2, the softmagnetic layers 11 and 12 may be respectively provided with theprotrusions 11P and 12P. The magnetic detector 20 may be providedbetween the protrusions 11P and 12P. This makes it possible to allow themagnetic flux F caused by the external magnetic field component in the Xaxis direction to concentrate on the magnetic detector 20. At thisoccasion, it is possible to bend, in the vicinity of the magneticdetector 20, the direction of the magnetic flux F along the in-planedirection of the X-Y plane as the direction of the magnetic sensing ofthe magnetic detector 20. Hence, it is possible to allow a direction ofextension of the soft magnetic layers 11 and 12 and a direction ofextension of each layer of the magnetic detector 20 to substantiallycoincide with each other, leading to easier manufacture.

2.2 Magnetic Field Detection Device 2A

Description is given next of a magnetic field detection device 2Aaccording to a first modification example in the forgoing secondembodiment, with reference to FIGS. 5A and 5B. FIG. 5A is a perspectiveview of an example of an overall configuration of the magnetic fielddetection device 2A. FIG. 5B illustrates an example of a cross-sectionalconfiguration of the magnetic field detection device 2A viewed in adirection of an arrow along a line VB-VB illustrated in FIG. 5A.

The magnetic field detection device 2A may include a plurality of themagnetic detectors 20 interposed between the pair of the soft magneticlayers 11 and 12. FIG. 5A illustrates, as an example, the six magneticdetectors 20 arranged in two rows and three columns, but there is nolimitation on the number of the plurality of the magnetic detectors 20and their arrangements. However, in one preferable but non-limitingexample, the plurality of the magnetic detectors 20 may be provided atthe same level. The plurality of the magnetic detectors 20 may beserially coupled as a whole by, for example, a plurality of leads 23 anda plurality of leads 24. Moreover, the protrusion 11P or the protrusion12P may be provided between any two adjacent ones of the magneticdetectors 20 (FIG. 5B). That way, in the magnetic field detection device2A, it is possible to increase an output as a whole, as compared to themagnetic field detection device 2. It is to be noted that FIG. 5A omitsillustration of the protrusion 11P and the protrusion 12P, for purposesof avoiding complications.

2.3 Magnetic Field Detection Device 2B

Description is given next of a magnetic field detection device 2Baccording to a second modification example in the forgoing secondembodiment, with reference to FIG. 6. FIG. 6 is a cross-sectional viewof an example of an overall configuration of the magnetic fielddetection device 2B. In the forgoing magnetic field detection device 2A,the soft magnetic layer 11 may be provided with the protrusion 11P,whereas the soft magnetic layer 12 may be provided with the protrusion12P. However, in the magnetic field detection device 2B according tothis modification example, solely the soft magnetic layer 11 may beprovided with the protrusion 11P. It is to be noted that solely the softmagnetic layer 12 may be provided with the protrusion 12P. In this caseas well, it is possible to cause conversion of the magnetic flux of theexternal magnetic field component in the Z axis direction, and to guidethe magnetic flux toward the magnetic detector 20, as compared to thecase of the magnetic field detection device 1 according to the firstembodiment that includes no protrusions.

According to the magnetic field detection device 2B of this modificationexample, although magnetic field detection sensitivity in the Z axisdirection lowers as compared to the magnetic field detection device 2A,it is possible to enhance flexibility in installation positions of themagnetic detector 20. For example, it is possible to dispose theplurality of the magnetic detectors 20 around the single protrusion 11P.Moreover, the flat surface 12S of the soft magnetic layer 12 as a baseis confronted with each of the magnetic detectors 20, making it easierto reduce variations in the plurality of the magnetic detectors 20. Forexample, it is easier to reduce variations in density of the magneticfluxes that cover the respective magnetic detectors 20, or to reducevariations in detection sensitivity of the plurality of the magnetismdetection devices 20. Furthermore, it is possible to eliminate a processof forming the protrusion 12P on the soft magnetic layer 12. This leadsto simplification of a manufacture process of the magnetic fielddetection device 2B, as compared to a manufacture process of themagnetic field detection device 2A.

2.4 Magnetic Field Detection Device 2C

Description is given next of a magnetic field detection device 2Caccording to a third modification example in the forgoing secondembodiment, with reference to FIG. 7. FIG. 7 is a cross-sectional viewof an example of an overall configuration of the magnetic fielddetection device 2C. In the forgoing magnetic field detection device 2,the soft magnetic layer 11 may be provided with the rectangularprotrusion 11P, whereas the soft magnetic layer 12 may be provided withthe rectangular protrusion 12P. However, the invention is not limitedthereto. The magnetic field detection device 2C according to thismodification example may include the protrusions 11P and 12P of asubstantially circular cone shape. Heads of the protrusions 11P and 12Pmay have a rounded shape. Moreover, in this modification example, partof the protrusions 11P and 12P may be level with part of the magneticdetector 20, in a direction substantially parallel to the X-Y plane.

According to the magnetic field detection device 2C of this modificationexample, the heads of the protrusions 11P and 12P may have the roundedshapes. Thus, a spatial change in the magnetic field strength around theheads of the protrusions 11P and 12P is smoothened, in detecting, forexample, the external magnetic field component in the Z axis direction.This leads to expectation of alleviation of detection errors caused bydeviations of the arrangement positions of the plurality of the magneticdetectors 20.

2.5 Magnetic Field Detection Device 2D

Description is given next of a magnetic field detection device 2Daccording to a fourth modification example in the forgoing secondembodiment, with reference to FIG. 8. FIG. 8 is a cross-sectional viewof an example of an overall configuration of the magnetic fielddetection device 2D. In the forging magnetic field detection device 2A,arrangement pitches of the plurality of the protrusions 11P andarrangement pitches of the plurality of the protrusions 12P maysubstantially coincide with each other. The plurality of the protrusions11P may be provided on the soft magnetic layer 11, whereas the pluralityof the protrusions 12P may be provided on the soft magnetic layer 12.Meanwhile, in this modification example, the arrangement pitches of theplurality of the protrusions 11P may be different from the arrangementpitches of the plurality of the protrusions 12P. FIG. 8 illustrates anexemplary case where the arrangement pitches P11 of the plurality of theprotrusions 11P are larger than the arrangement pitches P12 of theplurality of the protrusions 12P.

According to the magnetic field detection device 2D of this modificationexample, it is possible to adjust, as appropriate, the magnetic fielddetection sensitivity in each of the plurality of the magnetic detectors20, by changing distances from each of the plurality of the magneticdetectors 20 to the protrusions 11P and the protrusions 12P.

3. Experimental Examples 3.1 Experimental Examples 1-1 to 1-5

Simulations were carried out, to obtain distribution of the magneticfield strength around the magnetic field detection device according tothe example embodiment of the invention (e.g., the magnetic fielddetection device 1), with the external magnetic field in the Y axisdirection being applied to the magnetic field detection device.Conditions of the simulations were as follows. In the soft magneticlayers 11 and 12, the dimension LX in the X axis direction was 180 μm.The dimension LY in the Y axis direction was 140 μm. A thickness T was10 μm. The distance D from the soft magnetic layer 11 to the softmagnetic layer 12 was changed in a range from 10 μm to 150 μm bothinclusive. Specifically, in the experimental example 1-1, the distance Dwas 10 μm. In the experimental example 1-2, the distance D was 20 μm. Inthe experimental example 1-3, the distance D was 30 μm. In theexperimental example 1-4, the distance D was 100 μm. In the experimentalexample 1-5, the distance D was 150 μm. Results of the simulations areillustrated in FIGS. 9A to 9E. As illustrated in FIGS. 9A to 9E, as thedistance D, or a gap, from the soft magnetic layer 11 to the softmagnetic layer 12 increased, the magnetic flux came little by littleinto space between the soft magnetic layer 11 and the soft magneticlayer 12. As illustrated in FIG. 9A, with the distance D being small,the shielding effect produced by the soft magnetic layer 11 and the softmagnetic layer 12 was extremely high, and the magnetic flux barely cameinto the space between the soft magnetic layer 11 and the soft magneticlayer 12. Meanwhile, as the distance D increased, confirmed was gradualintrusion of the magnetic flux at a periphery of each of the softmagnetic layer 11 and the soft magnetic layer 12 (FIGS. 9B to 9E).However, it was found that disposing the magnetic detector in the spacebetween the soft magnetic layer 11 and the soft magnetic layer 12 madeit possible for the relevant magnetic detector to produce the shieldingeffect against the external magnetic field in the Y axis direction.

3.2 Experimental Examples 2-1 and 2-2 Experimental Example 2-1

Simulations were carried out, to obtain the distribution of the magneticfield strength in the vicinity of ends of the soft magnetic layers 11and 12, with the external magnetic field in the Y axis direction beingapplied to the magnetic field detection device according to the exampleembodiment of the invention (e.g., the magnetic field detection device1). The conditions of the simulations were as follows. The thickness Tof each of the soft magnetic layers 11 and 12 was 10 μ. The distance Dfrom the soft magnetic layer 11 to the soft magnetic layer 12 waschanged in a range from 10 μm to 30 μm both inclusive. Results of thesimulations are illustrated in FIG. 10.

Experimental Example 2-2

Similar simulations to those of the Experimental Example 2-1 werecarried out, except for the following conditions. The thickness T ofeach of the soft magnetic layers 11 and 12 was 20 μm. The distance Dfrom the soft magnetic layer 11 to the soft magnetic layer 12 was 20 μm,40 μm, or 60 μm. Results are illustrated in FIG. 11.

From the results in FIGS. 10 and 11, it was found that an intrusionlength LL was about a half of the distance D (LL≈D/2). The intrusionlength LL is a distance from the edge of the soft magnetic layer 11 or12 to a region with substantially constant magnetic field strength. Itwas therefore found that disposing the magnetic detector 20 at aposition retreating from the edge of the soft magnetic layer 11 or 12 byan amount equal to or larger than a half of a length corresponding tothe distance D made it possible to make more precise magnetic fielddetection.

3.3 Experimental Examples 3-1 to 3-8

Simulations were carried out, to obtain critical magnetic field strengthof the soft magnetic layers 11 and 12, with the external magnetic fieldin the Y axis direction being applied to the magnetic field detectiondevice according to the example embodiment of the invention (e.g., themagnetic field detection device 1). The conditions of the simulationswere as follows. The thickness T of each of the soft magnetic layers 11and 12 was 10 μm. The distance D from the soft magnetic layer 11 to thesoft magnetic layer 12 was 10 μm. The dimension LY of each of the softmagnetic layers 11 and 12 was 200 μm. The dimension LX of each of thesoft magnetic layers 11 and 12 was changed in a range from 20 μm to 800μm both inclusive (i.e., in a range of LX/LY=0.1 to 4 both inclusive).Results of the simulations were illustrated in FIG. 12.

As illustrated in FIG. 12, it was confirmed that higher criticalmagnetic field strength was obtained, in a case where LX/LY ranged from1 to 4 both inclusive, as compared to a case where LX/LY was smallerthan 1.

4. Other Modification Examples

Although the invention has been described in the foregoing by way ofexample with reference to the example embodiments and the modificationexamples, the technology of the invention is not limited thereto but maybe modified in a wide variety of ways. For example, in the technology ofthe invention, the shape of the soft magnetic layers is not limited tothose as described in the forgoing example embodiments. For example, theplanar shape is not limited to rectangles. As illustrated in FIGS. 13Ato 13D, various shapes may be adopted. In these cases as well, it isdesirable that a ratio of an in-plane maximum dimension b to a dimensiona in a direction orthogonal to a dimension including the in-planemaximum dimension b fall within a predetermined range.

Moreover, in the forgoing example embodiments, description is given withexemplification of the CPP MR element having the spin valve structure inwhich the direction of the magnetic sensing is the in-plane direction ofthe X-Y plane. However, the technology of the invention is not limitedthereto. For example, a current in plane (CIP) MR element or an MTJelement may be used. Other sensors than the MR elements may be alsoused. For example, a sensor such as a magnetic detector in which thedirection of the magnetic sensing is the Z axis direction may be alsoused. Non-limiting examples may include a Hall element. For example,FIGS. 14A and 14B illustrate a magnetic field detection device 3A and amagnetic field detection device 3B. In a case where the Hall element isutilized as the magnetic detector, as exemplified in FIGS. 14A and 14B,the Hall element 20H may be disposed at a position superposed in the Zaxis direction on the protrusion 11P or 12P (the protrusion). In otherwords, the Hall element 20H may be disposed directly above or directlybelow the protrusion 11P or 12P (the protrusion).

Moreover, the invention encompasses any possible combination of some orall of the various embodiments and the modification examples describedherein and incorporated herein.

It is possible to achieve at least the following configurations from theabove-described example embodiments and the modification examples of thedisclosure.

(1) A magnetic field detection device, including:

a first soft magnetic body and a second soft magnetic body that extendalong a first plane and are disposed in confronted relation in a thirddirection, the first plane including both a first direction and a seconddirection orthogonal to the first direction, and the third directionorthogonal to both the first direction and the second direction; and

a magnetic detector provided between the first soft magnetic body andthe second soft magnetic body in the third direction.

(2) The magnetic field detection device according to (1), in which

in the first soft magnetic body, the second soft magnetic body, or both,the following conditional expression [1] is satisfied,

1≤LX/LY≤4   [1]

where LX denotes a dimension in the first direction, and

LY denotes a dimension in the second direction.

(3) The magnetic field detection device according to (1) or (2), inwhich

the magnetic detector is a magneto-resistive effect element.

(4) The magnetic field detection device according to any one of (1) to(3), in which

the first soft magnetic body includes a first confronted surface that isconfronted with the second soft magnetic body,

the second soft magnetic body includes a second confronted surface thatis confronted with the first soft magnetic body,

a first angle formed by a first straight line with respect to the firstplane is equal to or smaller than 45°, the first straight line couplingthe magnetic detector to an edge of the first confronted surface, and

a second angle formed by a second straight line with respect to thefirst plane is equal to or smaller than 45°, the second straight linecoupling the magnetic detector to an edge of the second confrontedsurface.

(5) The magnetic field detection device according to (4), in which

a position of the edge of the first confronted surface and a position ofthe edge of the second confronted surface substantially coincide in thethird direction, and

the following conditional expression [2] is satisfied,

L≥D/2   [2]

where L denotes a distance from the edge of the first confronted surfaceto an edge of the magnetic detector, in a direction along the firstplane, and D denotes a distance from the first confronted surface to thesecond confronted surface.

(6) The magnetic field detection device according to any one of (1) to(5), in which

the first soft magnetic body includes a first confronted surface that isconfronted with the second soft magnetic body,

the second soft magnetic body includes a second confronted surface thatis confronted with the first soft magnetic body,

the first confronted surface, the second confronted surface, or bothinclude one or more protrusions.

(7) The magnetic field detection device according to (6), in which

part of the one or more protrusions is level with part of the magneticdetector, in a direction substantially parallel to the first plane.

(8) The magnetic field detection device according to any one of (1) to(7), in which

a first planar shape of the first soft magnetic body is substantiallyequal to a second planar shape of the second soft magnetic body, thefirst planar shape being parallel to the first plane, and the secondplanar shape being parallel to the first plane.

(9) The magnetic field detection device according to (2), in which

the second direction substantially coincides with a direction of anunwanted magnetic field component other than a magnetic field componentas a target of detection.

According to a magnetic field detection device of one illustrativeembodiment of the invention, a first soft magnetic body and a secondsoft magnetic body are provided, with a magnetic detector heldtherebetween in a third direction. Accordingly, the first soft magneticbody and the second soft magnetic body both act as magnetic yokes, withrespect to an external magnetic field component in the third direction.Meanwhile, the first soft magnetic body and the second soft magneticbody both act as magnetic shields, with respect to an external magneticfield component along a first plane.

According to the magnetic field detection device of the illustrativeembodiment of the invention, in the first soft magnetic body, the secondsoft magnetic body, or both, the following conditional expression [1]may be satisfied,

1≤LX/LY≤4   [1]

in which LX denotes a dimension in a first direction, and LY denotes adimension in a second direction.

This causes enhancement in critical magnetic field strength with respectto a magnetic field in the second direction in the first soft magneticbody, the second soft magnetic body, or both, leading to furtherenhancement in a magnetic shielding effect with respect to the magneticfield in the second direction along the first plane. It is to be notedthat the “critical magnetic field strength” as used here refers tostrength of an external magnetic field at which magnetization of therelevant magnetic body (in this case, the first soft magnetic body andthe second soft magnetic body) is saturated.

According to the magnetic field detection device of the illustrativeembodiment of the invention, the magnetic detector may be amagneto-resistive effect element. Moreover, the first soft magnetic bodymay include a first confronted surface that is confronted with thesecond soft magnetic body, whereas the second soft magnetic body mayinclude a second confronted surface that is confronted with the firstsoft magnetic body. A first angle formed by a first straight line withrespect to the first plane may be equal to or smaller than 45°. Thefirst straight line couples the magnetic detector to an edge of thefirst confronted surface. A second angle formed by a second straightline with respect to the first plane may be equal to or smaller than45°. The second straight line couples the magnetic detector to an edgeof the second confronted surface. In this case, a position of the edgeof the first confronted surface and a position of the edge of the secondconfronted surface may substantially coincide in the third direction,and the following conditional expression [2] may be satisfied,

L≥D/2   [2]

in which L denotes a distance from the edge of the first confrontedsurface to an edge of the magnetic detector, in a direction along thefirst plane, and D denotes a distance from the first confronted surfaceto the second confronted surface.

According to the magnetic field detection device of the illustrativeembodiment of the invention, the first confronted surface, the secondconfronted surface, or both may include one or more protrusions. In thiscase, part of the one or more protrusions may be level with part of themagnetic detector, in a direction substantially parallel to the firstplane.

According to the magnetic field detection device of the illustrativeembodiment of the invention, the first soft magnetic body and the secondsoft magnetic body exhibit a shielding effect with respect to theexternal magnetic field component along the first plane, while enhancingthe external magnetic field component in the third direction. Hence, itis possible to exhibit high performance in magnetic field detection,with respect to the external magnetic field component in the thirddirection.

Although the invention has been described in terms of exemplaryembodiments, it is not limited thereto. It should be appreciated thatvariations may be made in the described embodiments by persons skilledin the art without departing from the scope of the invention as definedby the following claims. The limitations in the claims are to beinterpreted broadly on the basis of the language employed in the claimsand not limited to examples described in this specification or duringthe prosecution of the application, and the examples are to be construedas non-exclusive. For example, in this disclosure, the term“preferably”, “preferred” or the like is non-exclusive and means“preferably”, but not limited to. The use of the terms first, second,etc. do not denote any order or importance, but rather the terms first,second, etc. are used to distinguish one element from another. The term“substantially” and its variations are defined as being largely but notnecessarily wholly what is specified as understood by one of ordinaryskill in the art. The term “about” or “approximately” as used herein canallow for a degree of variability in a value or range. Moreover, noelement or component in this disclosure is intended to be dedicated tothe public regardless of whether the element or component is explicitlyrecited in the following claims.

What is claimed is:
 1. A magnetic field detection device comprising: afirst soft magnetic body and a second soft magnetic body that extendalong a first plane and that are opposed to each other in a thirddirection, the first plane including a first direction and a seconddirection that is orthogonal to the first direction, the third directionbeing orthogonal to the first direction and the second direction, aplurality of protrusions provided between the first soft magnetic bodyand the second soft magnetic body in the third direction ; a magneticdetector provided between the first soft magnetic body and the secondsoft magnetic body in the third direction; and a lead provided so as tobe connected to the magnetic detector and supply a sense current to themagnetic detector, wherein the magnetic detector and the lead arerespectively provided in areas without overlapping any of the pluralityof protrusions in a direction along the first plane.
 2. The magneticfield detection device according to claim 1, wherein the plurality ofprotrusions is arranged in the first direction.
 3. The magnetic fielddetection device according to claim 1, wherein the magnetic detector hasa direction of magnetic sensing that is along the first plane, and themagnetic detector is provided at a position that is different from aposition superposed, in the third direction, on the plurality ofprotrusions and that is off an intermediate point between two of theplurality of protrusions, the two of the plurality of protrusions beingadjacent to each other along the first plane.
 4. A magnetic fielddetection device comprising: a soft magnetic body that extends along afirst plane, the first plane including a first direction and a seconddirection that is orthogonal to the first direction; a plurality ofprotrusions provided on a surface of the soft magnetic body, the surfaceextending along the first plane ; a magnetic detector opposed to thesurface of the soft magnetic body; and a lead provided so as to beconnected to the magnetic detector and supply a sense current to themagnetic detector, wherein the magnetic detector and the lead arerespectively provided in areas without overlapping any of the pluralityof protrusions in a direction along the first plane.
 5. The magneticfield detection device according to claim 4, wherein the plurality ofprotrusions is arranged in the first direction.
 6. The magnetic fielddetection device according to claim 4, wherein the magnetic detector hasa direction of magnetic sensing that is along the first plane, and themagnetic detector is provided at a position that is different from aposition superposed, in a third direction, on the plurality ofprotrusions and that is off an intermediate point between two of theplurality of protrusions, the third direction being orthogonal to thefirst direction and the second direction, the two of the plurality ofprotrusions being adjacent to each other along the first plane.
 7. Amagnetic field detection device comprising: a first soft magnetic bodyand a second soft magnetic body that extend along a first plane and aredisposed in confronted relation in a third direction with a non-magneticlayer in between, the first plane including both a first direction and asecond direction that is orthogonal to the first direction, the thirddirection being orthogonal to the first direction and the seconddirection, a magnetic detector provided between the first soft magneticbody and the second soft magnetic body in the third direction andseparated from both of the first soft magnetic body and the second softmagnetic body; and a lead provided so as to be connected to the magneticdetector and supply a sense current to the magnetic detector, whereinthe first soft magnetic body includes a first confronted surface that isconfronted with the second soft magnetic body, the second soft magneticbody includes a second confronted surface that is confronted with thefirst soft magnetic body, the first confronted surface, the secondconfronted surface, or both include a plurality of protrusions, or boththe first confronted surface and the second confronted surface includeone or more protrusions, magnetic detector includes a direction ofsensing along the first plane, and the magnetic detector and the leadare provided in an area between two adjacent protrusions along the firstplane without overlapping any of the plurality of protrusions in thethird direction.
 8. The magnetic field detection device according toclaim 7, wherein the magnetic detector and the lead are respectivelyprovided in areas without overlapping any of the plurality ofprotrusions in a direction along the first plane.
 9. A magnetic fielddetection device comprising: a first soft magnetic body and a secondsoft magnetic body that extend along a first plane and are disposed inconfronted relation in a third direction with a non-magnetic layer inbetween, the first plane including both a first direction and a seconddirection that is orthogonal to the first direction, the third directionbeing orthogonal to the first direction and the second direction, amagnetic detector provided between the first soft magnetic body and thesecond soft magnetic body in the third direction and separated from bothof the first soft magnetic body and the second soft magnetic body; and alead provided so as to be connected to the magnetic detector and supplya sense current to the magnetic detector, wherein the first softmagnetic body includes a first confronted surface that is confrontedwith the second soft magnetic body, the second soft magnetic bodyincludes a second confronted surface that is confronted with the firstsoft magnetic body, the first confronted surface, the second confrontedsurface, or both include a plurality of protrusions, or both the firstconfronted surface and the second confronted surface include one or moreprotrusions, magnetic detector includes a direction of sensing along thefirst plane, a center position of the magnetic detector in a directionalong the first plane is a different position from a positionoverlapping with a protrusion in the third direction, and the lead isprovided in an area between two adjacent protrusions along the firstplane without overlapping any of the plurality of protrusions in thethird direction.
 10. The magnetic field detection device according toclaim 9, wherein the lead is provided in area without overlapping any ofthe plurality of protrusions in a direction along the first plane.